Dispersion polymerisation process

Abstract

A process of polymerizing a polymerizable material in an inert organic liquid medium, in which the polymer formed from the monomer or monomers is insoluble, comprising dispersing the polymerizable material in the organic liquid in the presence of a finely, divided particulate material comprising an inorganic portion insoluble in the organic liquid medium and in combination therewith, preferably by covalent or ionic bonding, hydrocarbon chains containing at least 8 carbon atoms, the hydrocarbon chains being soluble in the organic liquid medium and heating the mixture to polymerize the polymerizable material to a required degree of polymerization. The process provides a means of stabilizing dispersion polymerizations which need to be carried out at very high temperatures to effect the polymerization.

We claim: 
     
       1. A process for the production of a condensation polymer dispersed in an inert organic liquid medium, comprising mixing reactants for forming the condensation polymer in the organic liquid in the presence of a finely divided particulate material having at least 95% by weight of particles with at least one dimension less than 1 micron and comprising an inorganic portion insoluble in the organic liquid medium, and in combination therewith hydrcarbon chains containing at least 8 carbon atoms, the hydrocarbon chains being at least partially soluble in the organic liquid medium, and heating the mixture to produce a condensation polymer of a required degree of polymerisation in the form of stably deflocculated, polymer particles. 
     
     
       2. A process according to claim 1 in which at least 95% by weight of the particles of the finely divided material have at least one dimension less than 0.1 micron. 
     
     
       3. A process according to any one of claims 1 to 2 in which the particulate material is a layer mineral. 
     
     
       4. A process according to claim 3 in which the layer mineral has been given a surface treatment to improve the dispersibility of the mineral in a liquid. 
     
     
       5. A process according to claim 4 in which the layer mineral has been surface treated to provide organophilic chains grafted onto the layer mineral by cation exchange. 
     
     
       6. A process according to any of claims 1 to 3 in which a finely divided, particulate material is used in combination with an organic, polymeric dispersing agent of molecular weight at least 500 carrying at least one reactive functional group per polymer chain. 
     
     
       7. A process according to claim 6 wherein the particulate additive has itself been surface treated to render it organophilic. 
     
     
       8. A process according to claim 1 in which polymerisation is conducted at a temperature in excess of 250° C.